My AGM to Lithium conversion

“With a 100ah AGM battery I could get 3 days run until the AGM was at 50%……With the Lithium I got over a week before I pulled the plug and the battery was still at 60%.”

AND by not fully recharging a Lithium battery every day you are not harming it…unlike a wet or AGM battery that needs full recharging daily.

3 tons wrote:
". With a 100ah AGM battery I could get 3 days run until the AGM was at 50%……With the Lithium I got over a week before I pulled the plug and the battery was still at 60%.”

A different and likely more precise way to state this might be, ‘With the 100a/hr AGM I had roughly 50 usable a/hrs, whereas with the 100a/hr LiFePO4 I had roughly 80 usable a/hrs, or 90 assuming a starting SOC of 100%…’ - me just saying…

Maybe the solar was not clipped by the extended absorption of the AGM and just put the power in the LFP. Ended up with more power at the end of the week.

Never quite understood the need to only use 80%of lifepo4 batteries when there advertised to get 2-3000 cycles at 100% discharge and 10 years service life then you still have 80%capacity after that.,0..That's 5X the average flooded battery and under $400 in some cases....

If I was back full timing, I wouldn't hesitate to use 100% of my lifepo4 batteries..But I'm pretty careful now not to go below 50% on my remaing AGM..lol

jaycocreek wrote:
Never quite understood the need to only use 80%of lifepo4 batteries when there advertised to get 2-3000 cycles at 100% discharge and 10 years service life then you still have 80%capacity after that.,0..That's 5X the average flooded battery and under $400 in some cases....

If I was back full timing, I wouldn't hesitate to use 100% of my lifepo4 batteries..But I'm pretty careful now not to go below 50% on my remaing AGM..lol

I agree completely. Top at 98% is fine and if it gets to 100% that is fine too. No reason to stop at the bottom except to avoid the point of losing all power at the cut-off.

People are being careless about saying what they mean in exact terminology, which could lead the unwary into trouble. :(

"Power" is in watt hrs, not AH and is one of WP's sneaky weasel words to do some of his smoke and mirrors stuff. :)

EG, note here what this particular LFP guide says:

" The BMS also disconnects the battery from the load if it is drained to less than 5% remaining charge (an over-discharge condition). An over-discharged battery typically has a voltage less than 11.5V (< 2.8V per cell)."

https://earthxbatteries.com/lithium-battery-series-parallel-operation/

IAW stay above 5% SOC if you can even stop it there (falling very fast)

Some think it is ok to zero% and experience shut off--except this LFP brand's BMS cuts off higher than that at 5%. There is a lot of confusion over how far down is zero!

It is all somewhat farcical IMO, but let's not get 3tons going off his meds again! :(

Point is to do what intinerant1 says, and just avoid the knees completely except the upper knee when needed to synch the monitor.

You absolutely need a monitor with LFPs to be ahead of the BMS cut offs. It is not a happy "look Ma, no hands" deal like some LFP owners seem to be trying to tell everyone.

You have to wonder how all those average RVers who got LFPs recently, who before had no clue how to look after their flooded batts, as is typical of the average RVer, are now able to keep their LFPs from an early death.

jaycocreek wrote:
Never quite understood the need to only use 80%of lifepo4 batteries when there advertised to get 2-3000 cycles at 100% discharge and 10 years service life then you still have 80%capacity after that.,0..That's 5X the average flooded battery and under $400 in some cases....

If I was back full timing, I wouldn't hesitate to use 100% of my lifepo4 batteries..But I'm pretty careful now not to go below 50% on my remaing AGM..lol

its because people see charts like this


then they apply traditional thinking to it from there older batteries and say well if we only use 70% of the capacity we can almost double the life of the battery. not realizing that they are already double the life and more than double the available power to start with. if you size your system properly you are rarely going to see anything remotly close to 100% capacity usage except for a break down of the charging system or some other emergency. my camper I went from two 208AH 6V to 300AH of LFP so with the old batteries it took me 3 days with out sun to to use about 70AH of the 100 available, so very little charging and I don't have anything but led lights, furnace, water pump, trace amounts for the fridge... with the new batheries that would be 12 days and not much issue of going that long with out sun. so I figure in all reality I will be doing less than 50% depth of discharge for the most part baring any emergency or failure. I may install a radio at some point though :B

time2roll wrote:

jaycocreek wrote:
Never quite understood the need to only use 80%of lifepo4 batteries when there advertised to get 2-3000 cycles at 100% discharge and 10 years service life then you still have 80%capacity after that.,0..That's 5X the average flooded battery and under $400 in some cases....

If I was back full timing, I wouldn't hesitate to use 100% of my lifepo4 batteries..But I'm pretty careful now not to go below 50% on my remaing AGM..lol

I agree completely. Top at 98% is fine and if it gets to 100% that is fine too. No reason to stop at the bottom except to avoid the point of losing all power at the cut-off.

when I set mine up I left the top at 100% and set my bottom to 12.1V. will I ever see the bottom, I doubt it unless I decide to install a microwave or something.

Steve

time2roll wrote:

jaycocreek wrote:
Never quite understood the need to only use 80%of lifepo4 batteries when there advertised to get 2-3000 cycles at 100% discharge and 10 years service life then you still have 80%capacity after that.,0..That's 5X the average flooded battery and under $400 in some cases....

If I was back full timing, I wouldn't hesitate to use 100% of my lifepo4 batteries..But I'm pretty careful now not to go below 50% on my remaing AGM..lol

I agree completely. Top at 98% is fine and if it gets to 100% that is fine too. No reason to stop at the bottom except to avoid the point of losing all power at the cut-off.

The ones that use lfp understand to use it all if needed or wanting to, if not no big deal. The ones don't use them don't understand that, keep regurgitating longer life but like most things the less you use them.... of course they'll last longer.

BFL says “It is all somewhat farcical IMO, but let's not get 3tons going off his meds again! :)

Ha!!…I’m afraid you might be confusing my handy-dandy BS Decoder Ring ‘for med’s’, but from the sound of your latest (in view of past ‘mischievous’ LFP postings of search record…), I for one will lean forward to welcome your apparent Good-Faith recovery :)…

Having said that, I wish you the best with your SiO2 battery (of silicon & O2) of which recall, I never once disparaged…

3 tons

It seems LFPs get their 100AH rating from running at 100 amps for an hour They then derive a 20 hr rating of 100 assuming Peukert is so low it does not count Meanwhile monitors are told to use say Peukert 1.1 ? for LFP instead of say l.3 for FLA

So that means if the rating was done at 100 amps then with at least some Peukert the 5 amp real 20 hr rate would be more than 100

Which might explain what some are seeing with their LFPs doing more than rated

That is on top of the mystery 100 vs 120AH thing that keeps coming up

Whatever, IMO just stay well above the low knee since it is not clear where that is

You can enjoy your LFP without pushing your luck on accidental low shut down